7: 2-hour-old male newborn with respiratory distress

Question 1

Fetal Effects of Maternal Hyperglycemia

Answer 1

High levels of maternal serum glucose d/r pregnancy result in hyperglycemia in the fetus. This stimulates the fetal pancreatic beta cells and the development of hyperinsulinemia. (Maternal insulin doesn’t cross the placenta.)

Question 2

Insulin is the primary anabolic hormone for fetal growth.

Answer 2

• -High levels in the third trimester result in increased growth of the insulin-sensitive organ systems (heart, liver and muscle) and a general increase in fat synthesis and deposition.
• -This combination of increased body fat, muscle mass, and organomegaly produces a macrosomic (LGA) infant.
• -Insulin-insensitive organs, such as the brain and kidneys, are not affected by the elevated insulin levels, and have appropriate size for gestational age.

Question 3

Control of diabetes during pregnancy is an important predictor of fetal outcome

Answer 3

• especially with regard to the risk of birth defects. The incidence of major malformations is directly related to the first-trimester HbA1c level:
• –Infants born to women with HbA1c levels > 12% have at least a 12-fold increase in major malformations.

Question 4

Large for gestational age (LGA): Definition and Etiology

Answer 4

Newborns with birth weight > 90th percentile. Although many LGA infants are constitutionally large, the most important pathologic etiology is maternal diabetes mellitus.

Question 5

Large for gestational age (LGA): Potential Clinical Problems

Answer 5

• -Large infants often must be delivered by c-section, by forceps, or vacuum extraction (all of which have associated complications)
• -Birth injuries are more common, such as fractured clavicle, brachial plexus injury, and facial nerve palsy
• -Hypoglycemia is especially common in LGA infants born to diabetic mothers

Question 6

Appropriate for gestational age (AGA): Definition and Etiology

Answer 6

Newborns with birth weights between the 10th and 90th percentiles.

Question 7

Small for gestational age (SGA): Potential Clinical Problems

Answer 7

• Temperature instability (hypothermia)
• Inadequate glycogen stores (hypoglycemia)
• Polycythemia and hyperviscosity

Question 8

Small for gestational age (SGA): Definition and Etiology

Answer 8

• NBNs w/ birth weights <10th percentile. An infant may have low birth weight d/t prematurity, but low birth weight also results from many other causes. Depending on the cutoff level used, up to 70% of SGA infants are small simply due to constitutional factors determined by maternal ethnicity, parity, weight or height.
• An infant is diagnosed as being SGA at time of birth.
• Note that the terms SGA and intrauterine growth restricted (IUGR) are both used in the literature. While they are often used synonymously, they are not the same thing:
• A growth-restricted fetus is one that has not reached its growth potential at a given gestational age due to one or more causative factors.
• A fetus is noted to be IUGR during the pregnancy.

Question 9

Signs of Respiratory Distress

Answer 9

findings of tachypnea, retractions, and grunting are classic symptoms of respiratory distress from any cause.

Question 10

When Does Tachypnea Preclude Oral Feeding?

Answer 10

• -Many infants with respiratory rates of 60-80 per minute tolerate oral feeds, but some may need nasogastric feeding or IV fluids if respiratory distress worsens with feeding.
• -Many infants with respiratory rates of > 80 per minute will have difficulty with both oral and nasogastric feedings and will often require intravenous fluid support.

Question 11

Breastfeeding

Answer 11

• -Separation of mother and infant poses a challenge for the successful establishment of breastfeeding.
• If the infant cannot successfully breastfeed because of his tachypnea, it will be important that the mother begin pumping her breasts as soon as possible after delivery. This will initiate milk production and ensure an adequate supply when the baby is able to feed at the breast.
• In the meantime, the infant would be fed expressed breast milk, supplemented with formula as needed while breast milk volumes are low in the first 24-48 hours after birth.
• Pumping breast milk is also psychologically helpful for mothers at a very stressful time

Question 12

“late preterm”

Answer 12

Infants born between 34 weeks gestation and 36 weeks, 6 days

Question 13

Late preterm infants are at risk for a number of problems. Hospital discharge requires that each of the following has been ruled out or has resolved.

Answer 13

● Hypothermia
● Hypoglycemia
● Respiratory distress
● Apnea
● Hyperbilirubinemia 
● Feeding difficulty

Question 14

definition of hypoglycemia in the neonate

Answer 14

target glucose screen value prior to routine feeds is > 45 mg/dL (2.5 mmol/L).

Question 15

Glucose transport and stabilization

Answer 15

• In infants of diabetic mothers, high levels of maternal serum glucose d/r pregnancy result in hyperglycemia in the fetus.
• This stimulates the fetal pancreatic beta cells and the development of hyperinsulinemia. (Maternal insulin does not cross the placenta.) -As a result of hyperinsulinemia, infants of diabetic mothers are at risk for significant hypoglycemia after birth.

Question 16

If the baby is symptomatic from hypoglycemia

Answer 16

intravenous infusion of dextrose should be started immediately as it guarantees a stable source of glucose.

Question 17

Asymptomatic babies with hypoglycemia

Answer 17

breast fed or given pumped breast milk or formula by bottle. If an infant is unable to be fed orally, for example, because of respiratory distress, nasogastric feeding is an option

Question 18

Developmental Dysplasia of the Hip (DDH): Clinical features include:

Answer 18

• Partial or complete dislocation

- Instability of the femoral head.

Question 19

Developmental Dysplasia of the Hip (DDH): Risk factors include

Answer 19

Breech position (30-50% of DDH cases occur in infants born in the breech position) Gender (9:1 female predominance)
Family history

Question 20

DDH Screening recommendations (AAP)

Answer 20

• Serial clinical examinations of all infants’ hips to the age of 12 months
• Hip imaging for female infants born in the breech position
• Optional hip imaging for boys born in the breech position
• Optional hip imaging for girls with a positive family history

Question 21

Newborn hospital discharge considerations

Answer 21

• f/u
• feeding: breastfed infant will typically feed on demand every 2-4 h, feeding 10-15 min on each side.
• jaundice
• Vit D
• car seat
• sleep position and co-sleeping

Question 22

Chest X-ray Findings: Transient tachypnea of the newborn (TTN)

Answer 22

“wet” looking lungs, no consolidation, and no air bronchograms.

Question 23

Chest X-ray Findings: Respiratory distress syndrome (RDS)

Answer 23

diffuse reticulogranular appearance of the lung fields (“ground glass appearance”) and air bronchograms

Question 24

Chest X-ray Findings: Diaphragmatic hernia

Answer 24

Most often a diaphragmatic hernia develops on the left side. A radiograph shows air-filled loops of bowel in the left side of the chest, displacing the heart and mediastinum to the contralateral side

Question 25

Chest X-ray Findings: neonatal PNA

Answer 25

appear similar to those of an infant with TTN, but the clinical findings would be much more concerning for sepsis.

Question 26

Differential Diagnosis for Tachypnea in the Newborn: Respiratory distress syndrome (RDS) (1/9)

Answer 26

• Caused by a deficiency of lung surfactant and delayed lung maturation
• Can occur as late as 37 weeks’ gestation
• Most common cause of respiratory distress in premature infants
• Increased risk in infants of diabetic mothers

Question 27

Differential Diagnosis for Tachypnea in the Newborn: Transient tachypnea of the newborn (TTN) (2/9)

Answer 27

• Result of delayed clearance of fluid from the lungs following birth
• Much more common in infants born to diabetic mothers and in infants born by c-section

Question 28

Differential Diagnosis for Tachypnea in the Newborn: Pneumothorax (3/9)

Answer 28

• -Caused by a collection of gas in the pleural space with resultant collapse of lung tissue
• -Common risk factors are mechanical ventilation or underlying lung disease (especially meconium aspiration or severe infant respiratory distress syndrome).
• -While relatively uncommon, always an important consideration in an infant with respiratory distress
• -More likely in a premature infant with RDS

Question 29

Differential Diagnosis for Tachypnea in the Newborn: Meconium aspiration (4/9)

Answer 29

Infants who aspirate meconium in utero or at the time of delivery often present with symptoms of respiratory distress, including tachypnea

Question 30

Differential Diagnosis for Tachypnea in the Newborn: Hypoglycemia (5/9)

Answer 30

• May be seen in infants of diabetic mothers d/t the chronic hyperinsulinemic state that occurred during gestation
• Can be more pronounced in premature infants
• Tachypnea is a nonspecific response to this metabolic derangement

Question 31

Differential Diagnosis for Tachypnea in the Newborn: Hypothermia (6/9)

Answer 31

• Low core temperature can lead to tachypnea
• Premature newborns are more at risk to become hypothermic because of their relatively high surface area to weight ratio and lack of adipose tissue for insulation

Question 32

Differential Diagnosis for Tachypnea in the Newborn: Cardiac abnormalities (7/9)

Answer 32

• Maternal diabetes is a RF for the development of structural congenital heart disease, in addition to transient HOCM (inc circulating insulin serves as a growth factor to myocardium)
• Common congenital heart defects can cause tachypnea d/t pulmonary overcirculation; these include VSD, PDA, and an atrioventricular canal defect (AVC). The tachypnea is typically not present in the NBN pd, and develops as the pulmonary vascular resistance falls, typically by 6-8 wks.
• Coarctation of the aorta can lead to tachypnea d/t pulmonary venous congestion from left heart obstruction. This occurs around 3-7 days of age as the PDA closes.
• Some cyanotic defects (such as total anomalous pulmonary venous return, TAPVR) can also present in infancy with tachypnea (in addition to cyanosis).

Question 33

Differential Diagnosis for Tachypnea in the Newborn: Neonatal sepsis (8/9)

Answer 33

• Can present initially with tachypnea and progress to more severe illness rapidly
• Risk factors include:
• –Maternal colonization with Group B strep
• –Prolonged rupture of membranes (> 18 hours)
• –Delivery < 37 weeks
• –Maternal fever or chorioamnionitis

Question 34

Differential Diagnosis for Tachypnea in the Newborn: Congenital diaphragmatic hernia (9/9)

Answer 34

• Malformation resulting from a defect in the development of the diaphragm
• Allows the passage of organs from the abdomen into the chest cavity and severely impairs lung development
• Most defects occur on the left side
• Occurs in 1 out of every 2,200 to 5,000 live births
• Most common type (accounting for > 95% of cases) is the Bochdalek hernia, which is located posterolaterally
• Absent breath sounds or presence of bowel sounds on one side of the chest are important diagnostic clues

Question 35

Hypoglycemia

Answer 35

a common presentation in an infant born to a diabetic mother with poor glucose control during her pregnancy. The increase in maternal serum glucose stimulates fetal pancreatic beta cells to increase insulin production, and this hyperinsulinemic state leads to hypoglycemia when the placental glucose supply is discontinued after delivery. At < 4 hours of life, a glucometer reading of < 25 mg/dL without symptoms or < 40 mg/dL with symptoms would require intervention to correct the hypoglycemic state. This infant has signs of hypotonia, with absence of flexed posture and weak suck, and a blood glucose reading of 39 mg/dL, making hypoglycemia the most likely diagnosis.

Question 36

Pneumothorax

Answer 36

collapse of lung tissue secondary to air accumulation in the pleural space. Risk factors for pneumothorax in an infant include previous intubation or underlying lung disease (such as severe respiratory distress syndrome). Characteristic physical exam findings include asymmetric breath sounds or decrease in breath sounds on one side. This infant has good air movement in bilateral lung fields, making this diagnosis less likely.

Question 37

Neonatal sepsis

Answer 37

most commonly caused by GBS, Listeria and E. coli, transmitted from mother to baby. Additional risk factors include premature rupture of membranes (> 18 hours prior to delivery), preterm delivery, and chorioamnionitis. Infants may present with fever, trouble breathing, jaundice, and lethargy.

Question 38

A male infant weighing 3200 grams is born to a G1P1 female at 39 weeks’ gestational age via planned C-section. Maternal PMH is unremarkable, and GBS status is unknown. Apgars are 7 and 8 at 1 and 5 minutes of life, respectively. The delivery is uncomplicated, and the infant initially appeared in good condition. However, one hour following delivery the infant develops increasing respiratory distress. RR is assessed as 90 breaths/min. All other vital signs are within normal limits. On exam, the infant is acyanotic with rapid respirations and robust capillary refill. Chest x-ray shows bilateral lung fields with the appearance of “a radio-opaque line of fluid in the horizontal fissure of the right lung.” No air bronchograms are noted. What is the most likely etiology of the infant’s respiratory distress?

Answer 38

Transient tachypnea of the newborn (TTN) is the most likely underlying etiology. This condition is caused by residual fluid in the infant’s lungs following delivery, and usually resolves within several days. It is more common in babies delivered via C-section, as the normal mechanical force of labor that helps expel fluid from the lungs is lacking. Babies with TTN and other forms of respiratory distress are often unable to nurse and require feeding via NG tube until respiratory status stabilizes.

Question 39

A newborn baby boy is born at 30 5/7 weeks’ gestation after induction of labor for the severe maternal preeclampsia. He is noted to have subcostal and intercostal retractions, grunting, nasal flaring, persistent cyanosis, and tachypnea 30 minutes after delivery. Apgars were 6 (-2 for color, -1 for breathing and -1 for tone) and 7 (-2 for color and -1 for breathing) at 1 and 5 minutes, respectively. Due to lack of prenatal care and the mother’s presentation with severe preeclampsia, betamethasone x 1 was given during induction, but she did not receive a second dose prior to delivery. A chest x-ray is obtained, which reveals diffuse ground-glass appearance and air bronchograms bilaterally. What is the most likely diagnosis?

Answer 39

This choice is correct. The baby boy is preterm, and his mother received only one dose of betamethasone, which puts him at increased risk for developing infant RDS, which is caused by insufficient surfactant. His physical exam and chest x-ray findings are consistent with RDS.